This is a reupload. I found out that the old version of the mod was severely bugged and caused the game to break after a Sim aged up, so I deleted it in an emergency as it was not safe to use. After spending hours hunting down the problem, I managed to fix it. If you have the old version, please remove it immediately and replace it with the new one. I wouldn't normally take the entire mod down if I discovered a bug, but this one was severe and game-breaking, and I thought I wouldn't be able to fix it at all.
I bring you a new trait for The Sims 4, the Serious trait.
The Serious trait has the following effects…
Sims will not suffer from low Fun until they drop into the extreme levels, and even then, they only get a +2 Bored moodlet.
Sims will gain all mental skills slightly faster.
Sims will gain most social skills (as most related to jokes and pranks) slower, with the exception of Charisma, which they will gain slightly faster.
Sims will get an Energized moodlet from a day at work that would be boring to other Sims.
Playful emotional auras will emit a Bored moodlet instead.